THE FUNDAMENTAL PHYSIOLOGICAL ACTIONS 27 



ception of new particles, food in one form or another, from the ex- 

 terior. The nearest approach to it is probably exhibited by the 

 resting state into which some of the lower animals, as the wheel- 

 animalcules, pass when dried slowly at a low temperature; the 

 drying acting by checking the nutritive processes, which would 

 otherwise have prevented the reattainment of molecular equilib- 

 rium. All signs of movement or other change disappear under 

 these circumstances, but as soon as water again soaks into their 

 substance and disturbs the existing condition, then the so-called 

 " spontaneous " movements recommence. If, therefore, we use the 

 term spontaneity to express a power in a resting system of particles 

 of initiating changes in itself, it is possessed neither by living nor 

 not-living things. But if we simply employ it to designate changes 

 whose primary cause we do not recognize, and whose cause was in 

 many cases long antecedent to the changes which we see, then the 

 term is unobjectionable and convenient, as it serves to express 

 briefly a phenomenon presented by many living things and finding 

 its highest manifestation in many human actions. It then, how- 

 ever, no longer designates a property peculiar to them. A steam- 

 engine with its furnace lighted and water in its boiler may be set in 

 motion by opening a valve, and the movements thus started will 

 continue spontaneously, in the above sense, until the coals or water 

 are used up. The difference between it and the living cell lies not 

 in any spontaneity of the latter, but in its nutritive powers, which 

 enable it to replace continually what answers to the coals and water 

 of the engine. 



Protoplasm. The cell-body was formerly regarded as essentially 

 made up of a single substance, which was named protoplasm: and 

 now that its structure is known to be complex the term is retained 

 as a convenient one for that mixture of spongioplasm and hyalo- 

 plasm which constitutes the main bulk of the bodies of most cells. 

 With the protoplasm other things are frequently present, the most 

 important of which are either materials undergoing anabolic 

 changes but not yet completely built up into protoplasm, or 

 katabolic materials resulting from the chemical degradation of 

 protoplasm: these secondary matters, mingled with the completed 

 protoplasm, are conveniently spoken of as the cell deutoplasm or 

 paraplasm. As between the spongioplasm and hyaloplasm there 

 are still some differences of opinion as to which is the more im- 



